Exercise equipment has been designed to facilitate a variety of exercise motions. For example, treadmills allow a person to walk or run in place; stepper machines allow a person to climb in place; bicycle machines allow a person to pedal in place; and other machines allow a person to skate and/or stride in place. Yet another type of exercise equipment has been designed to facilitate relatively more complicated exercise motions and/or to better simulate real life activity. Such equipment typically converts a relatively simple motion, such as circular, into a relatively more complex motion, such as elliptical.
U.S. Pat. No. 4,185,622 to Swenson discloses an exercise machine that generates elliptical exercise motion. Left and right foot supporting links have rearward ends which are rotatably coupled to respective cranks, and forward ends which are rotatably coupled to respective rocker links or guides. As a result, the rearward ends of the foot supporting links rotate in a circle together with the cranks; the forward ends of the foot supporting links move in reciprocal fashion together with the rocker links; and all intermediate points on the foot supporting links move through respective elliptical paths (which are similar in length but decrease in height as a function of distance from the crank axis). An advantage of this arrangement is that the heel of a user rises faster than his toe as the foot supporting link begins moving forward, and the heel of the user falls faster than the toe as the foot supporting link begins moving rearward.
U.S. Pat. No. 5,279,529 to Eschenbach also discloses an exercise machine that generates elliptical exercise motion. Left and right foot supporting links have rearward ends which are rotatably coupled to respective cranks, and forward ends which are rotatably coupled to respective rocker links on one embodiment (shown in FIG. 4 of the Eschenbach patent), and which are rotatably coupled to respective rollers on another embodiment (shown in FIG. 8 of the Eschenbach patent). As a result, the rearward ends of the foot supporting links rotate in a circle together with the cranks; the forward ends of the foot supporting links move in reciprocal fashion together with the rocker links or the rollers; and all intermediate points on the foot supporting links move through respective elliptical paths (which are similar in length but decrease in height as a function of distance from the crank axis). This arrangement similarly causes the heel of a user to rise faster than his toe as the foot supporting link begins moving forward, and the heel of the user to fall faster than the toe as the foot supporting link begins moving rearward.
Another feature of the machines shown in the Eschenbach patent is that the person's feet may be selectively moved to different positions along the foot supporting links. As a result, all portions of the user's feet may be positioned for movement through respective elliptical paths during rotation of the cranks. In other words, as compared to the Swenson machine, the person's feet may be positioned for movement through somewhat flatter elliptical paths on the Eschenbach machines.
U.S. Pat. No. 5,242,343 to Miller also discloses an exercise machine that generates elliptical exercise motion. Left and right foot supporting links have rearward ends which are rotatably coupled to respective cranks, and forward ends which are rotatably coupled to respective rocker links on one embodiment (shown in FIG. 4 of the Miller patent), and which are rotatably coupled to respective rollers on another embodiment (shown in FIG. 1 of the Miller patent). As a result, the rearward ends of the foot supporting links rotate in a circle together with the cranks; the forward ends of the foot supporting links move in reciprocal fashion together with the rocker links or the rollers; and all intermediate points on the foot supporting links move through respective elliptical paths (which are similar in length but decrease in height as a function of distance from the crank axis). This arrangement similarly causes the heel of a user to rise faster than his toe as the foot supporting link begins moving forward, and the heel of the user to fall faster than the toe as the foot supporting link begins moving rearward.
Another feature of the machines shown in the Miller patent is that the foot supporting platforms occupy relatively forward positions along the foot supporting links. As a result, all portions of the user's feet are positioned for movement through respective elliptical paths during rotation of the cranks. Moreover, as compared to the Eschenbach machine, the person's feet are positioned for movement through somewhat flatter elliptical paths on the Miller machines. It is somewhat problematic to describe or compare the respective locations of and/or paths traveled by a person's feet on the Miller machines and the Eschenbach machines because the analysis depends upon the size of a person's feet. What can be said with certainty is that the Miller machines simulate a relatively flatter striding motion because the foot platforms are positioned to remain entirely forward of the crank diameter at all times.
As compared to the Swenson machine, the Miller machines use a relatively larger crank diameter to generate a longer stride. In order to generate a comfortable amount of rise in relation to the stride length, the foot platforms must be spaced a significant distance forward of the crank axis (to “dilute” the vertical component of the striding motion).
Generally speaking, a common shortcoming of many prior art machines (including those discussed above) is that a common linkage arrangement generates both the horizontal component of foot travel and the vertical component of foot travel. As a result, any desired increase in the length of foot motion necessarily involves an increase in the height of foot motion, as well. Unfortunately, this fixed aspect ratio is contrary to real life activity, since a person does not typically lift his legs higher and higher while taking strides which are longer and longer.
As a result of the direct relationship between horizontal foot travel and vertical foot travel, undesirable compromises were made to arrive at the prior art machines discussed above. For example, the Swenson machine is relatively compact, but the user's heels travel through paths of motion which are nearly circular, and the user's toes travel through paths of motion which are nearly arcuate. At the other extreme, the Miller machines guide all portions of the user's feet through relatively flat elliptical paths of motion, but the machines are significantly longer than the Swenson machine. In fact, most prior art machines combine a relatively large crank diameter in order to generate a sufficiently long striding motion, and relatively long foot supports in order to reduce the associated vertical component of the striding motion (making the foot paths relatively flatter than they are long).
As suggested by the foregoing discussion, a need remains for a relatively compact elliptical motion exercise machine which generates a relatively long striding motion having a natural aspect ratio between stride length and stride height.